M51 was discovered by French astronomer Charles Messier in 1774. It was considered a nebula at that time because it just looked like a fuzzy blob in a telescope. Some seventy years later Irish astronomer William Parsons (Lord Rosse) looked at it through his 72-inch telescope, the largest in the world at that time. He was the first to see its spiral structure.

The latest article from the Astronomy site at BellaOnline.com is:

Nebulas – Ten Facts for Kids
Nebulae are great clouds of gas and dust in the spaces between the stars. Some of them are made from dying stars. Others are the nurseries for new stars. Here are ten facts about these surprising objects.